The invention relates to photochromic spirofluorenopyran compounds as well as to their use. The inventive compounds are photochromic pyran compounds, which are derived from 9H-fluorene, the carbon atom in the 9-position belonging to a further ring system and thus forming a spiro linkage site.
Certain classes of dyes have long been known which, when irradiated with light of particular wavelengths, especially with sunlight, reversibly change their color. This is due to the fact that these dye molecules are converted by light energy into an excited state, which they leave once again, returning to their initial state, when the supply of energy is interrupted. These photochromic dyes include different pyran systems, which already are described in the state of the art with different basic systems and substituents.
Pyrans, especially naphthopyrans and larger ring systems derived from these, are 5at the present time the class of photochromic compounds, on which most of the work has been done. Although the first patent application was filed as early as 1966 (U.S. Pat. No. 3,567,305), it was possible only in the 1990s to develop compounds, which appear to be suitable for use in eyeglasses. A suitable class of pyran compounds is, for example, the 2,2-diaryl-2H-naphtho(1,2-b)pyrans or the 3,3-diaryl-3H-naphtho(2,1-b)pyrans, which exhibit different colorations, such as yellow, orange or red-orange, in the excited state. A further class of photochromic compounds, which is of interest, is the indene-annelated naphthopyrans, which absorb at longer wavelengths because of their larger ring system. These can be systems, which are derived either from the 2H-naphtho( 1,2-b)pyrans or the 31H-naphtho(2,1-b)pyrans, and are produced from the respective naphthopyran systems by the annelation at the f side of the naphthalene part.
Several publications are concerned with indene-annelated naphthopyrans derived from 2H-naphtho( 1,2-b)pyrans. International Patent Application Nos. WO 97/48762 and WO 97/48993 and U.S. Pat. No. 5,723,072 describe naphthopyran compounds with a substituted or unsubstituted indeno group, the 2,1 positions of which are annelated with the f side of the naphthalene portion of a 2H-naphtho(1,2-b)pyran, the pyran ring having special substituents. In WO 97/48993 and U.S. Pat. NO. 5,723,072, an unsubstituted, a monosubstituted or a disubstituted heterocyclic ring at the g, h, i, n, or p side of the indenonaphthopyran, can be annelated to this basic system. Accordingly, indeno(2,1-f)naphtho(1,2-b)pyrans with a very large variation of possible substituents are disclosed; however, ring formation between the substituents R.sub.1 and R.sub.2 at carbon atom No. 13 with formation of a spiro carbon atom is not described in these publications. A Spiro linkage is disclosed only directly at the pyran ring at the substituents B and B'.
Published International Patent Application Nos. WO 96/14596 and WO 98/32037, International Patent Application No. PCT/DE 98/02820, and U.S. Pat. Nos. 5,645,767 and 5,698,141 also describe photochromic indene-annelated naphthopyran dyes, which are derived from 2H-naphtho(1,2-b)pyran, as well as the compositions containing them and a method for their synthesis. In U.S. Pat. No. 5,698,141, an unsubstituted, a monosubstituted or a disubstituted heterocyclic ring at the g, h, i, n, o or p side of the indenonaphthopyran can additionally be annelated to this basic system. Of the very extensive list of substituents, quite special Spiro compounds have also been included, namely those systems with a spiro heterocyclic group, in which, including the Spiro atom at the 13 position of the base system, a 5-membered to 8-membered ring, which always carries two oxygen atoms, is present.
The different known photochromic dyes are, however, associated with disadvantages which, when they are used in sunglasses, significantly affect the wearing comfort. The longwave absorption in the excited and in the unexcited state of the known dyes is inadequate. The temperature sensitivity of the darkening is too high and, at the same time, the brightening is frequently too slow. Moreover, the known dyes, and consequently the photochromic eyeglasses produced with them, frequently have an insufficient service life. Furthermore, a rapid decrease in performance and/or strong yellowing may be noted.
Moreover, the prior art includes hardly any references to the positions at which a pyran is to be substituted and to the substituents themselves, in order to achieve a particular longwave absorption maximum. In cases in which certain substitution patterns fix an absorption maximum, the kinetic properties, such as the darkening and brightening rates, the temperature dependence, etc. are also fixed therewith. Until now, it has not been possible to affect the kinetics at will in both directions, faster or slower, while having practically no effect on the absorption maximum.